Air circuit breakers as described within U.S. Pat. Nos. 3,095,489 entitled "Manual Charging Means for Stored Energy Closing Mechanisms of Electric Circuit Breakers" and 3,084,238 entitled "Ratchet Mechanism for Charging a Closing Spring in an Electric Circuit Breaker" include operating mechanisms that are mainly exposed to the environment. Since the air circuit breakers are rated to carry several thousand amperes of current continuously, the exposure to convection cooling air assists in keeping the operating components within reasonable temperature limits.
Such air circuit breakers are usually provided with a motor operator such as described in U.S. Pat. No. 4,167,988 entitled "Ratcheting Mechanism for Circuit Breaker Motor Operator" or a manual handle as described in U.S. Pat. No. 3,729,065 entitled "Means for Charging A Stored Energy Circuit Breaker Closing Device" for charging the powerful closing springs contained within the air circuit breaker operating mechanism.
As described within the aforementioned U.S. Pat. No. 4,167,988, the ratchet mechanism includes a driving pawl coupled with the motor operator for incrementally advancing a ratchet wheel coupled with the circuit breaker operating mechanism. The patent further suggests the use of a holding prop to hold the pawls out of engagement with the ratchet wheel until the closing springs have fully discharged to protect the pawls and the ratchet wheel from potential damage. When the contacts have become closed, the circuit breaker operating mechanism components are exposed to allow an operator to manually release the holding prop in order for the holding pawl to again become operative in recharging the circuit breaker closing spring.
When the circuit breaker closing springs are brought to their fully-charged conditions, it is important that the springs do not become inadvertently discharged while an operator has hold of the charging handle in order to avoid damage to the ratchet mechanism and the associated air circuit breaker contacts. An early arrangement of a latching means to prevent rotation of a closing springs charging handle is found in U.S. Pat. No. 4,475,021 entitled "Air Circuit Breaker". A more recent arrangement is found in U.S. patent application Ser. No. 08/878,596 entitled "Circuit Breaker Operating Handle Torque Compensation Module" filed on Jun. 19, 1997.
With such circuit breakers having their contacts in the OPEN position and the closing springs fully charged, a manual closing button or a remotely-controlled closing solenoid, interacts with the holding prop described earlier, to allow the closing springs to become released from the holding prop and drive the contacts to the CLOSED position.
One purpose of the invention, accordingly, is to describe an arrangement whereby the closing button and the closing solenoid are enabled to displace the holding prop and allow the contacts to become driven to the CLOSED position.